The present invention relates to an image forming apparatus, an image forming system and an image forming method wherein a plurality of image forming apparatuses such as copying machines are connected through networks, image data obtained through reading are transmitted and received reciprocally, and plural image forming apparatuses share an amount of image output to output images in parallel. A system wherein image data are transmitted and received reciprocally and plural image forming apparatuses output images in parallel by sharing image output with one another is hereinafter called a tandem image forming system, and an image forming method employing that system is called a tandem image forming method.
As a tandem image forming system, there has been known a system wherein a plurality of image forming apparatuses are connected through exclusive cables. When connected through exclusive cables, even when an image forming apparatus which has read an image is arranged to transmit image data to all other image forming apparatuses connected through exclusive cables, no bad influences have been exerted on other equipment because of the closed nature of the system, and no problem has been caused in particular. Accordingly, there has been taken a structure wherein an image forming apparatus whose copy key has been pressed reads an image to become a master machine, and it sends image data thus read to the exclusive cable without considering targets in particular, then other image forming apparatuses connected to the exclusive cable become slave machines to receive image data sent from the master machine. Further, in the case of a tandem image forming system employing a general purpose network, there has been structured so that a server for centralized control of each image forming apparatus is provided separately to control each image forming apparatus.
For example, when no centralized control server is provided in general purpose networks such as an internet, each copying machine can not get knowledge of a copying machine of a target, and thereby can not operate as a tandem copying machine. Therefore, it necessary to input the target manually in each copying machine, which causes cost. It is also possible to consider to arrange a tandem copying machine by broadcasting image data simply and thereby by sending data to all equipment. This method, however, is not preferable because large data of image are sent through all networks in this method and communications of other equipment are interrupted.
As stated above, each copying machine needs to be capable of controlling tandem copying in the tandem copying system, and an object of the invention is, in consideration of the problem mentioned above, to provide a tandem image forming system and a tandem image forming method wherein tandem operations can be carried out, without a special control server, on general purpose networks to which plural image forming apparatuses such as copying machines are connected.
The above object can be attainined by the following structure and method.
An image forming apparatus, comprises:
an interface connected to a network so as to send or receive data;
a memory to store a resident communication program to communicate with another image forming apparatus through the network, wherein the resident communication program establishes channel information regarding data communication among a plurality of image forming apparatus connected with the network based on data regarding other image forming apparatus sent through the network;
a recording device to form an image on a recording medium based on image data; and
an overall control device to control overall the image forming apparatus comprising the interface, the memory and the recording device.
An image forming system, comprises:
a plurality of image forming apparatus each connected to a network capable of conducting a broadcast communication;
each of the plurality of image forming apparatus comprising a resident communication program to communicate with another image forming apparatus through the network, wherein the resident communication program establishes channel information regarding data communication among a plurality of image forming apparatus connected with the network based on data regarding other image forming apparatus sent through the network; and
each of the plurality of image forming apparatus sending image data to or receiving the image data from other image forming apparatus on the basis of the channel information through the network and sharing image formation with others so as to conduct the image formation in parallel together with others.
An image forming method of outputting images in parallel by a plurality of image forming apparatus connected to a network capable of conducting a broadcast communication, comprising steps of:
sending data regarding an image forming apparatus itself through the network;
receiving data regarding other image forming apparatus sent through the network;
establishing channel information regarding data communication among a plurality of image forming apparatus by a resident communication program based on the received data regarding the other image forming apparatus sent through the network;
sending the channel information to the other image forming apparatus through the network; and
outputting images in parallel by the plurality of image forming apparatus based on the channel information.
Further, the above object may be attained by the following preferable structure.
Namely, in copying machines capable of conducting tandem operations in the general purpose network constituted with an equipment (hub) connecting two copying machines each having a communication interface or connecting plural copying machines, the following conditions of arrangement need to be satisfied.
(1) A resident communication program for communicating with other copying machines can be operated in each copying machine.
(2) A network can conduct communication for distributing given data to tandem programs of all copying machines on the network.
(3) A unique number (identification (ID) number) capable of comparing sizes is allocated to each copying machine.
In the tandem image forming system of the invention in which plural image forming apparatuses such as copying machines are connected to a network and image data are exchanged through the network to form images, each of the plural image forming apparatuses operates a resident communication program for communicating with other image forming apparatuses, the network mentioned above can conduct broadcast communication and establishes channel information for the resident communication program with broadcast message in accordance with the state of operation of each image forming apparatus, and tandem image forming operations are carried out by conducting communication on the aforesaid network by the use of the established channel information.
In the invention, channel information which conducts tandem image forming operations in the network to which a plurality of image forming apparatuses are connected is established in accordance with the state of operation of each image forming apparatus. It is therefore possible to comply with a change in the structure of the network. For example, when a certain image forming apparatus is not operating, channel information is established by excluding the image forming apparatus, or when a certain image forming apparatus is operated afterward, establishment of channel information can be made taking that image forming apparatus into consideration. Further, each image forming apparatus controls another image forming apparatus each other so that each control information and image data can be exchanged through network communication of the channel information. Therefore, it is possible to operate a tandem image forming apparatus such as a tandem copying machine without a special control server in the general purpose network. Since it is possible to operate a tandem image forming apparatus on an ordinary network employing a exclusive cable, therefore, less plant investment is required, and a tandem image forming system which is more complicated or more flexible than a exclusive cable can be constituted. It is further possible to structure a tandem image forming system simply at low cost, because a special control server which controls each image forming apparatus is not required.
It is further possible to arrange so that the aforesaid resident communication program of each image forming apparatus compares identification information given to each image forming apparatus to determine one of the plural image forming apparatuses as a server, and the image forming apparatus thus determined controls as a serve other image forming apparatuses as a client. Owing to the comparison of identification information of each image forming apparatus, a server and a client can be determined and the server can control each client.
When an arrangement is made so that the time of the server is synchronized with that of the client, it is convenient for control of transmission of image data. It is further possible to accurately conduct measurement of efficiency of data transmission which will be described later.
It is further possible to arrange so that data transmission efficiency is measured between the aforesaid server and the client, and the tandem image forming operations mentioned above are conducted based on the measured transmission efficiency. Due to this, when large amount of data can not be transmitted because of low quality of the line, for example, or when the transmission speed is low, it is possible to take measures to reduce an amount of data by enhancing the rate of compression for image data. It is further possible to take means to notify waiting time by indicating, on a graph, the time required for communication which can be obtained from an amount of data and the rate of transmission.
Further, the tandem image forming method of the invention is a tandem image forming method in which plural image forming apparatuses are connected to a network, and image data are exchanged through the network for image forming, wherein a resident communication program for each of the plural image forming apparatuses to communicate with other image forming apparatuses is operated, and the network can conduct broadcast communication, and a step to establish channel information for the resident communication program in accordance with broadcast message and the state of operation of each image forming apparatus and step to conduct tandem image forming operations by performing communication on the network by the use of the established channel information are included.
Further, in the tandem image forming method, it is possible to arrange so that a step in which the resident communication program of each image forming apparatus compares identification information given to each image forming apparatus to determine one of the plural image forming apparatuses as a server, is further included, and this image forming apparatus thus determined controls, as a server, other image forming apparatuses as a client. It is further possible to arrange so that a step in which the time of the server is synchronized with that of the client before the tandem image forming operations and a step to measure the data transmission efficiency between the server and the client are included, and the tandem image forming operations are conducted based on the efficiency of transmission obtained through the aforesaid measurement.